Second-order inelastic dynamic analysis of cable-stayed bridges using rectangular concrete-filled steel tubular columns

An advanced numerical method is proposed in this paper for the second-order inelastic dynamic analysis of cablestayed bridges using rectangular concrete-filled steel tubular (CFST) columns under earthquake loadings for the first time. The proposed method can exactly predict the nonlinear response of the bridges by using only one element per member in simulating the structural model. This comes from considering both the geometric and material nonlinearities in a fiber beam-column element and a catenary cable element. In the fiber beam-column element, the geometric nonlinearities are captured by applying the stability functions, whereas the material nonlinearities are evaluated by tracing the uniaxial cyclic stress-strain curves of each fiber on the cross-sections, which are located at the integration points along the member length. A computer program was developed based on Newmark's average acceleration algorithm to solve the nonlinear equations of motion. The accuracy and computational efficiency of the proposed program were verified by comparing the predicted results with the experimental results, and the results obtained from the commercial software SAP2000 and ABAQUS. The proposed program is promising as a useful tool for practical designs for the nonlinear inelastic dynamic analysis of cable-stayed bridges.